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Table 2 Adjusted mean mammographic density measures according to reproductive and hormonal exposures among premenopausal women

From: Predictors of mammographic density among women with a strong family history of breast cancer

  

Premenopausal women (n = 97)

 

Percent Density (%)

 

Dense Area (cm2)

 

Non-Dense Area (cm2)

n

Mean1 PD

95% CI1

P 1

n

Mean1 DA

95% CI1

P 1

n

Mean1 NDA

95% CI1

P 1

Age at menarche

 <13 years

32

29.9

20.0-41.8

 

28

31.1

17.2-49.2

 

28

80.1

50.4-116.7

 

 ≥13 years

65

28.2

19.6-38.3

0.69

60

35.3

22.5-51.1

0.49

60

98.2

69.8-131.6

0.16

Parity

 Nulliparous

26

32.5

21.5-45.8

 

23

37.1

21.4-57.0

 

23

93.6

60.5-133.8

 

 Parous

71

28.1

19.7-38.1

0.33

65

33.8

21.3-49.2

0.61

65

93.9

66.1-126.6

0.98

Total live births2

 1

21

41.6

27.2-59.0

ref

19

50.1

28.0-78.6

ref

19

71.7

39.0-114.3

ref

 2

35

28.8

17.8-42.3

0.04

32

32.9

17.2-53.7

0.06

32

84.7

52.2-125.0

0.40

 ≥3

15

29.1

15.3-47.3

0.12

14

33.0

13.7-60.8

0.14

14

82.5

42.6-135.3

0.58

Breastfeeding2

 Never

4

34.9

13.2-67.0

 

4

44.1

13.7-91.8

 

4

77.9

26.9-155.3

 

 Ever

66

31.7

20.7-45.1

0.79

61

36.0

19.8-56.9

0.64

61

81.5

50.7-119.6

0.90

Breastfeeding duration2

 <11 months

30

32.7

18.7-50.5

 

31

41.9

21.2-69.6

 

31

76.5

41.4-122.4

 

 ≥11 months

40

31.7

20.6-45.2

0.87

34

34.9

18.9-55.8

0.43

34

82.8

51.3-121.8

0.69

OC use

 Never

10

29.6

17.5-44.9

 

9

33.2

15.8-57.1

 

9

72.4

38.4-117.2

 

 Ever

87

28.5

19.9-38.7

0.87

79

34.5

21.9-50.0

0.89

79

97.3

69.1-130.3

0.18

Duration of OC use

 <9 years

40

37.4

25.2-52.0

 

37

41.5

24.6-62.8

 

37

79.9

50.0-116.8

 

 ≥9 years

47

33.0

22.1-46.0

0.32

42

35.9

20.4-55.9

0.39

42

86.1

54.9-124.2

0.60

  1. 1Adjusted least-square means, 95% confidence intervals, and P-values are from analyses using square root-transformed mammographic density measures. The adjusted least-square means and 95% confidence intervals were back-transformed
  2. 2Among parous women only
  3. All models were adjusted for age (continuous) and BMI (continuous) at the time of mammogram, parity (continuous), and mammogram modality (digital image, film scanned by study team, film scanned by imaging centre). The parity (total live births) and breastfeeding models were additionally adjusted for age at first birth (continuous). OC, oral contraceptives
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BMC Cancer

ISSN: 1471-2407

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